GP35 Group Build kicked off today.

[markfj]

Here are a couple shots of a GP(something?) either being scrapped or repaired. These photos show the frame construction method Brian was talking about in video 9. I think these images came from a discussion on the Diesel Detailer, but I’m not sure. You can also see the coupler pocket details and buffer plate clearly. Also looking forward to getting some of Brian’s 3D buffer plates; just need to find someone to mill down the coupler pads first.





Also curious to know if the end plate on the frame was changed to the design Brian shows (the plate with the semicircular cutout) on later GP30 & 35 models. I took some photos last summer of Reading GP30 5513 (1st GP30 built, 1962) and GP35 3640 (phase 1b1, built 1964) and it looks like neither have end plates that cross the frame. Since these locomotives were early versions I’m guessing EMD changed the design on subsequent models for some reason (maybe to improve frame strength?).


GP30 5513 rear of tank


GP30 5513 front of tank


GP35 3640 rear of tank (hard to see, but looks like frame is similar to GP30 5513)


Thanks, Mark

[Deleted]

Good stuff Mark.

The next video will answer your question as to the slope plate design. Yes it does change. I made the mistake of using the GP7 design and have since fixed it on the model and you will see it in the next video. I have a manufacturers drawing of the slope plate in the video also.

The first couple photos you show are of I think a GP38-2. The buffer plate changed after the GP35 series and early GP40. The best way to see it is look at the CB&Q GP40. The early units have the exact same nub pilot plate as the phase II GP35 which also use the same buffer plate. When the GP40 pilot plate design was changed, it received the notched buffer plate. The notch is at the front on each side plate. The front edge of the side plate steps in about an 1" at the coupler opening.

I still have to add this notched buffer plate to my Shapeways page. This will happen when I start work on my EJ&E GP38-2's.

Brian

[markfj]

Here is more GP35 frame info that I saved from a post on ProtoModeler. (I think that website is now on Facebook only, so I can’t post a direct link to this discussion.) The poster was confirming Brian’s measurements on the GP35 frame and deck height (he claims to have the actual EMD drawings!). Real good info; glad I took the time to copy and save it, wish I got the photos too. (Detailed info like this is what made ProtoModeler a great site, too bad it’s gone.)


Posted 18 January 2015 - 03:36 PM
on ProtoModeler
Just arrived on the forum - that is a really gorgeous model! Looking forward to seeing the final result.

I noticed that there has been a lot of discussion about the frame height between the Phase 1 and Phase 2 GP35, and I think I can clear things up.

I have detailed EMD mechanical drawings for the underframe of several models, including the early GP35 and the GP39 (which, aside from a few small details, is the same as the frame for the GP38 and GP40). From the diagrams, I can confirm the following:

- The top of the underframe is explicitly stated as 60.75" for the GP35 and 62.25" for the GP39 - a difference of 1.5".

- The height from the rail to the bottom of the underframe and the dimensions of the coupler pocket/draft gear are the same on both models, with a nominal 33.875" coupler height.

- While not listed in the drawings, extrapolating the height of the main frame based on other dimensions gives a frame height of about 14.5" for the GP35 above the trucks (the "fishbelly" part is about 24") and 16" for the GP39 - so the height difference is entirely the result of a thicker main frame on the GP38-40.

- The side frame is thicker on the early GP35 (10" at the ends, 7" in the middle) than on the GP40 (8" at the ends, 5" in the middle). As a result, much more of the main frame (an additional 3.5") is visible below the side frame on the GP40 than the GP35.

Other measurements I've been able to find have given a nominal deck height of 60.25" to 60.75" for the GP35, and 61.75" to 62.5" for the GP40. The difference of 1.5" also correlates with railroad diagrams that list the height over the cab as 14' 4.5" for the GP35 and 14' 6" for the GP40 - which, given the EMD cab/hood height of 9' 4.25" above the frame, results in deck heights of 60.25" for the GP35 and 61.75" for the GP40.

The above dimensions are for the early GP35, and I don't have actual dimensions for a Phase 2 GP35. However, I've taken photo measurements of the main underframe dimensions of the Phase 2 GP35 - main frame thickness, side frame thickness, fuel tank profile, jacking pad height and design, stepwell dimensions - and they all line up exactly with the dimensions for the GP40, save for the thinner side frame above the air reservoirs (3" instead of 5"). This suggests that the main frame dimensions for the Phase 2 GP35 were carried over to the GP40, and that the Phase 2 GP35 therefore has the same deck height as the GP40 - about 62", or 1.5" higher than the early GP35.

In response to some of the photos posted, the close-up photos of the front truck of two BNSF GP39 rebuilds are a bit misleading, since the apparently higher ride height on the later unit is a result of the photo perspective (the first photo was taken at a stronger zoom and less of an upward angle).

The photo of BNSF GP60B's 337 and 338 is a perfect illustration of what I've found to be by far the biggest factor affecting frame height: Wheel wear. While the other wheels aren't visible, the rearmost wheel of 337 is visibly more worn than 338, and 337 is also slightly slanted up to the left (which would lower the coupler). But more to the point, I tried measuring the full-size version of the photo, and the height between the bottom of the underframe and the axle centerlines is, for all intents and purposes, identical between the two units (538 px for 337, 540 px for 338). This leaves wheel wear (and rail height) as the sole explanation for the height difference.

A wheel may lose 3" in diameter by the time it's condemned, assuming a new rim thickness of 2.5" and a minimum thickness of 1". In other words, all else being equal, a GP35 with new wheels will ride about the same height as a GP40 with worn wheels, despite the nominal 1.5" difference. This variation is why I've always measured the walkway height based on the axle centerlines. Whenever I've measured between the axle centerlines and the top of the walkway - whether from photos I've taken of in-service units or physically measuring preserved units - I've found the measurement has always fallen within 1" (and usually within less than 0.5") of the nominal value.

(Edit: Additionally, I think the real-world measurements posted by Brian above actually confirm this distinction. The average of all six Phase 1 GP35 deck heights (59.625") plus the average of the six values for wheel wear (0.79" / 2 = 0.395") gives a height of 60.02", while the average of the two deck heights for the Phase 2 unit (60.875") plus the average wheel wear (1.125" / 2 = 0.563") gives a height of 61.44", for a difference of 1.42").

Hope this clears things up a bit!

[bar]

Interesting thread. The construction of locomotive and car frames hasn't changed much in 100 years, except for the shift from rivets to welded construction.


Is there a good way to estimate actual dimensions from a photograph in, say, Photoshop? If you know one key dimension (such as wheel diameter)?

[jonklein611]

May 17, 2018 7:14:30 GMT -8 bar said:

Interesting thread. The construction of locomotive and car frames hasn't changed much in 100 years, except for the shift from rivets to welded construction.


Is there a good way to estimate actual dimensions from a photograph in, say, Photoshop? If you know one key dimension (such as wheel diameter)?

Potentially, but it really depends on the angle of the photo, what lens was used, if any correction was used to account for the lens' distortion, etc.

[Deleted]

Update video #10. See original post.

Brian

[CRcsxns]

Thanks Brian! Great stuff!!

[Deleted]

Again, see original post for latest video update. Video #11.

Brian

[Deleted]

Next video added. See original post.

Brian

[nebrzephyr]

Hi Brian. On the latest video concerning painting the wheel sets. I use MicroScale Micro Mask on the axle tips. Just apply a small amount with a toothpick. After painting, the mask just flips off using the tip of a #11 blade. Thought you might like to try,

Bob

[Deleted]

Thank you Bob. I have masked the wheel tips before and quit honestly. To much work. Scraping the paint off is not a chore and it comes off VERY easily.

Thank you though for bringing it up. I did not mention that in my video and others may like to try it over scraping the paint off.

Brian

[Deleted]

Another video uploaded just now. See original post for #13.

Brian

[Deleted]

Another video uploaded. See original post for #14.

Brian

[nstophat]

Brian;

I love it, thanks for doing this series, can't wait for the next video. I do have a question, I know you mention not sealing the finish on the wheels, as they shouldn't be touched, but in regards to wheels in the modern HTCR series trucks on the SD70 DC & AC units, half of the wheels are constantly exposed, and while folks shouldn't be molesting the models, what would you suggest as a sealer, Pigment Fixer from Ammo / MIG or something else?

Regards,
Russ

[Deleted]

Jun 11, 2018 14:58:32 GMT -8 nstophat said:

Brian;

I love it, thanks for doing this series, can't wait for the next video. I do have a question, I know you mention not sealing the finish on the wheels, as they shouldn't be touched, but in regards to wheels in the modern HTCR series trucks on the SD70 DC & AC units, half of the wheels are constantly exposed, and while folks shouldn't be molesting the models, what would you suggest as a sealer, Pigment Fixer from Ammo / MIG or something else?

Regards,
Russ

Anything is going to change or alter the color tones. 

If you are going to apply any sealer, wait a few weeks for the oil coat to thoroughly dry. Then apply a thin layer of pigment setting solution. Be sparing on it. Just a few touches with a fine brush and let is spread out on its own. This will darken the tone a little.

Brian

[nstophat]

Thanks Brian.

[Deleted]

Some more updates posted. See original post.

[nebrzephyr]

Brian, enjoying the video series. In #15 you grit blasted the truck parts. Might I ask what you used as "grit". In the distant past I used aluminum oxide. But for the last several years I have just been using baking soda.

Thanks. Bob

[Deleted]

Bob,

I use aluminum oxide. It started out as 180 grit. After about 10 or more years of use. It is probably 1000 grit.

I'll keep using aluminum oxide. It works good.

Brian

[slowfreight]

May 17, 2018 4:20:15 GMT -8 markfj said:

Here is more GP35 frame info that I saved from a post on ProtoModeler. (I think that website is now on Facebook only, so I can’t post a direct link to this discussion.) The poster was confirming Brian’s measurements on the GP35 frame and deck height (he claims to have the actual EMD drawings!). Real good info; glad I took the time to copy and save it, wish I got the photos too. (Detailed info like this is what made ProtoModeler a great site, too bad it’s gone.)

Thanks for the vote of confidence. I was a moderator at Protomodeler, and it hurt to shut it down. But the forum hosting software changed one too many times and we just didn't have the energy to reformat everything a third time. Unfortunately, I didn't save a lot of the good work we posted over there.